The invention relates to a method of cleaning a slip ring which is arranged so as to be rotatable about an axis of rotation, is supported by a frame and a circumferential surface of which is provided with at least one signal or power track which extends concentrically about the axis of rotation.
Slip rings of this kind, customarily provided with a plurality of signal and/or power tracks, are used in a variety of devices, for example, in a tomography device controlled by a computer, for example, as disclosed in U.S. Pat. No. 5,018,174. Other devices, for example radar installations and the like, also utilize such slip rings.
During operation of devices provided with such slip rings it is from time to time necessary to clean the tracks in the slip rings in order to ensure continued correct transfer of signals and/or power. The customary method used to clean signal and/or audio tracks consists in the removal of the brush assemblies, co-operating with the tracks, from the supporting members for the brush assemblies which form part of the frame, and in providing said supporting members with supporting devices which support elongate rods. At the ends of said rods there are mounted cushions which are made of cotton or a similar material and serve to wipe the tracks clean.
The mounting of such a cleaning device is a very time-consuming operation and, moreover, it has been found in practice that the cleaning is often inadequate and that the cotton cushions leave particles and dirt behind in the tracks.
It is an object of the invention to provide a method of the kind set forth wherein the drawbacks of the method used thus far are mitigated.
This object can be achieved according to the invention in that a lining moistened with a liquid is pressed against the circumferential surface provided with the track, and in that the slip ring is rotated while keeping the lining pressed against the circumferential surface. Preferably, the lining may be formed by a chamois or synthetic material or cloth.
Surprisingly, it has been found that the tracks provided in slip rings can thus be effectively cleaned in a fast and simple manner, without it being necessary to remove parts, such as brush assemblies or the like, before commencing the cleaning of the slip ring. A track can be effectively cleaned by means of the chamois without the chamois itself giving off dirt.
Moreover, a plurality of adjacently situated tracks can be simultaneously cleaned by means of a chamois, so that particularly fast cleaning is achieved.
It has been found in practice that, whereas the cleaning of a slip ring by means of the described known method requires a period of time of approximately four hours, such cleaning can be performed by means of the method according to the invention within a period of time of approximately 20 minutes. The method according to the invention thus offers a substantial saving in respect of maintenance of the slip rings and, moreover, the device in which the slip ring is used need be put out of operation for a short period of time only so as to allow cleaning of the slip ring.
Alcohol is a preferred liquid for moistening or drenching the chamois.
Furthermore, use is preferably made of a lining made of a synthetic material, because such a synthetic lining has a constant thickness across its entire surface, as opposed to a natural chamois leather whose thickness is liable to vary across its surface.
Particularly thorough cleaning of a track can be realized by pressing the cloth by means of a member whose surface contacting the cloth has a shape which is essentially complementary to the circumferential surface of the slip ring wherein the track is provided. The cloth can then be suitably pressed against the boundary walls of the track.
According to a further aspect of the invention a particularly effective device for carrying out the method according to the invention is obtained by providing the device with a support which is to be connected to the frame supporting the slip ring and in relation to which the lining such as a chamois can be fixed, the support supporting a pressure strip for pressing the chamois against the circumferential surface of the slip ring provided with a track, said pressure strip being adjustable, relative to the support, between a first position, in which the pressure strip does not exert a pressure on the chamois, and a second position in which the pressure strip presses the chamois cloth against the circumferential surface of the slip ring.
The use of such a device enables the device to be quickly and simply connected to the frame supporting the slip ring, without it being necessary to remove brush assemblies or the like whereas, after the device has been installed and the chamois fitted between the pressure strip and the circumferential surface provided with a track, the chamois can be effectively pressed against the circumferential surface.
The chamois can be fitted in a location which is generally suitably accessible and visible, so that the device can be simply checked for correct operation.
The pressure strip is advantageously resiliently supported by the device, so that during operation the pressure strip is movable in a direction extending mainly perpendicularly to the circumferential surface of the slip ring. The pressure strip can thus follow irregularities, if any, in the circumferential surface of the slip ring during operation, thus maintaining suitable contact between the circumferential surface of the slip ring and the chamois.